Field of the Invention
The present disclosure relates to a technical field of punching technique, more particularly, to a punching device for punching network nodes on a mold insert and a method of punching network nodes by using the same.
Description of the Related Art
Thin film transistor liquid crystal display (TFT-LCD) technique has become very mature, and is applied from a small size screen of mobile phone to a large size screen of television.
A backlight module of a LCD panel includes a light source, a reflection plate, a light guide plate, a diffusion plate, a prism sheet and an optical sheet, or the like. Major techniques of the LCD panel are focused on optical design of the liquid guide plate, mold design and manufacturing, and precision injection molding technology. One of the most crucial requirements for the light guide plate is to improve brilliance and to evenly distribute light rays. Therefore, property of the light guide plate is directly correlated to a yield of the entire backlight module.
Currently, mainstream technologies of the light guide plate include a printing technique and a non-printing technique, wherein the former is to evenly distribute printing materials of high light scattering substance onto a bottom surface of the light guide plate, while the latter is to form V-shaped microgrooves by using a precision mold insert, and then to manufacture the light guide plate complying with optical characteristics by means of a manufacturing mode of injection molding.
High precision light guide plate requires accurate V-shaped grooves having an identical depth, an identical pitch between adjacent grooves, and smooth surfaces of the V-shaped grooves, and so on.
One existing technique employs driving a tool bit with air pressure and injecting it onto the mold insert, so as to form cavities (i.e., network node). It is not easy to adjust the air pressure, so that hole diameters of the formed cavities and tolerance of their depths would dramatically change. This has a relatively large effect on the yield of the light guide plate. In addition, the spacing of the bit and the mold insert cannot be adjusted, and thus this demands the surface of the mold insert has a relatively high flatness. Slight change of the surface height will produce a relatively large effect on the depth of the network nodes.